Have you ever wanted to better understand an email you received? Where it came from, the path it took, who, etc? Start looking at email headers. Two common analyzers to start with:
Google - https://toolbox.googleapps.com/apps/messageheader/arrow-up-right
Microsoft - https://appsource.microsoft.com/en-us/product/office/wa104005406?tab=overview&exp=ubp8arrow-up-right
Last updated 2 years ago